JP4939325B2 - Aluminum alloy plate for lithographic printing plate and method for producing the same - Google Patents

Description

  The present invention relates to an aluminum alloy plate for a lithographic printing plate, and more particularly to an aluminum alloy plate for a lithographic printing plate that is suitable for roughening by electrochemical etching and has excellent productivity during production, and a method for producing the same.

  In general, an aluminum alloy plate is used as a support for lithographic printing plates (including offset printing plates), and the support is rough from the viewpoint of improving the adhesion of the photosensitive film and improving the water retention of the non-image area. In recent years, the surface of the aluminum alloy plate for the support is roughened by electrochemical etching because of its excellent plate-making suitability and printing performance, and continuous processing with coil materials. The approach to surface is developing rapidly.

  As an aluminum alloy plate capable of obtaining a relatively uniform electrolytic surface roughening by electrochemical etching treatment, a material equivalent to A1050 (aluminum purity 99.5%) or a material added with a small amount of alloy components based on A1050 equivalent material is used. Applied, for example, a material containing a small amount of Pb (see Patent Document 1), and a small amount of Cu, so that the Cu concentration in the surface layer portion is higher than the Cu concentration in a region deeper than the surface layer portion. A material (see Patent Document 2) has been proposed.

  Conventionally, these aluminum alloy materials for lithographic printing plates are homogenized, hot-rolled ingots, cold-rolled, and subjected to intermediate annealing in the middle of cold-rolling to recrystallize the rolled plate surface. After forming the structure, by performing secondary cold rolling, the generation of pits during the electrochemical etching process is made uniform, and the occurrence of streaks when the process as a printing plate is performed is prevented. A decrease in productivity and an increase in manufacturing costs due to annealing are inevitable, and improvements are desired.

As a method of obtaining an aluminum alloy plate for lithographic printing plates by performing cold rolling without performing annealing treatment after hot rolling, in hot rolling consisting of hot rough rolling and hot finish rolling, The starting temperature is set to 450 ° C. or more, rolling is performed at a rolling speed of 50 m / min or more from the starting pass, a reduction amount of 30 mm or more, or a one-pass reduction ratio of 30%, and the end temperature of hot rough rolling is set to 300 to A method for controlling recrystallization of the plate surface by setting the temperature to 370 ° C. and then setting the end temperature of hot finish rolling to be 280 ° C. or higher and winding the coil as a coil has been proposed (see Patent Document 3).
JP-A-8-337835 JP 2000-108534 A Japanese Patent Laid-Open No. 11-335761

  In order to omit intermediate annealing, it is necessary to recrystallize at the stage of winding as a coil after completion of hot finish rolling. It is important that the recrystallized grain size does not become coarse and is fine and uniform as in the material subjected to the intermediate annealing, and that the degree of recrystallization of the plate surface layer part is uniform.

  For the purpose of obtaining an aluminum alloy material for a lithographic printing plate capable of achieving uniform and fine pit formation in electrolytic treatment by improving electrolytic characteristics, the inventors have used a conventionally proposed material as a base for component composition. As a result of re-examination and testing and examination of a manufacturing method that omits the intermediate annealing, a material containing Pb and having a Pb concentration in the surface layer portion higher than that in a region deeper than the surface layer portion is effective. In order to produce such a textured aluminum alloy sheet without intermediate annealing, hot rough rolling start temperature, material retention from hot rough rolling end to hot finish rolling, It was found that controlling the finishing temperature of hot finish rolling is important.

  The present invention has been made as a result of further tests and examinations based on the above knowledge, and the purpose of the present invention is to restore the surface layer portion of the plate at the stage of winding as a coil after the hot finish rolling. The degree of crystal is uniform, the recrystallized grains are fine and uniform, can be cold-rolled to the final thickness without intermediate annealing after hot rolling, and the moderate Pb enrichment at the surface layer part The resulting aluminum alloy plate for lithographic printing plates has uniform pit generation during electrochemical etching and no streak when processed as a printing plate, and improves productivity and reduces manufacturing costs An object of the present invention is to provide a method for producing an aluminum alloy plate for a lithographic printing plate that makes it possible.

  In order to achieve the above object, an aluminum alloy plate for a lithographic printing plate according to claim 1 is composed of Si: 0.03 to 0.15%, Fe: 0.2 to 0.6%, Ti: 0.005 to 0. 0.05%, Pb: 2 to 30 ppm, having a composition composed of the balance aluminum and inevitable impurities, an average recrystallized grain size in the direction perpendicular to the rolling direction of the surface layer portion being 50 μm or less, and 0.2 μm from the surface The Pb concentration in the surface layer portion to the depth is 100 to 400 times the average Pb concentration.

  An aluminum alloy plate for a lithographic printing plate according to claim 2 is characterized in that, in claim 1, Cu: 0.05% or less is contained.

  An aluminum alloy plate for a lithographic printing plate according to claim 3 is characterized in that, in claim 1 or 2, Mg: less than 0.05% is contained.

The aluminum alloy plate for a lithographic printing plate according to claim 4 is the deposit according to any one of claims 1 to 3, wherein a precipitate having a particle size of 1 to 10 µm exceeds 4000 to 10,000 particles / mm ² and a particle size of more than 10 µm in the matrix. The number of objects is distributed at 100 pieces / mm ² or less.

  A method for producing an aluminum alloy plate for a lithographic printing plate according to claim 5 comprises homogenizing the aluminum alloy ingot according to any one of claims 1 to 3 in a temperature range of 500 to 610 ° C for 1 hour or more. The hot rough rolling is performed at a start temperature of 430 to 500 ° C. and an end temperature of 400 ° C. or more. After the hot rough rolling, the hot rough rolled material is placed for 60 to 300 seconds before the start of hot finish rolling. Hold and recrystallize the surface of the hot rough rolled material, then perform hot finish rolling, finish hot finish rolling at a temperature of 330 ° C. or higher, and perform cold rolling with a workability of 80% or higher. It is characterized by.

  According to the present invention, after completion of hot finish rolling, at the stage of winding as a coil, the degree of recrystallization of the plate surface layer portion is uniform, the recrystallized grains are fine and uniform, and intermediate annealing after hot rolling is performed. Can be cold-rolled to the final thickness without carrying out the process, and an appropriate Pb enrichment in the surface layer can be obtained, and the generation of pits during the electrochemical etching process is uniform, and the process as a printing plate is performed. An aluminum alloy plate for a lithographic printing plate that does not cause streak in the case of a lithographic printing plate, and a method for producing an aluminum alloy plate for a lithographic printing plate that can improve productivity and reduce manufacturing costs.

  The significance of the components contained in the aluminum alloy plate for a lithographic printing plate of the present invention and the reason for limitation will be explained. Fe forms an Al—Fe intermetallic compound and coexists with Si between Al—Fe—Si based metals. The compounds are formed and the recrystallization structure is refined by the dispersion of these compounds, and these compounds become the starting point of pit generation to make the formation of pits uniform during electrolytic treatment and to distribute the pits finely. The preferable content of Fe is in the range of 0.2 to 0.6%, and if it is less than 0.2%, the distribution of the compound becomes nonuniform, and the formation of pits during the electrolytic treatment becomes nonuniform. If it exceeds 0.6%, a coarse compound is produced, and the uniformity of the roughened structure is lowered.

  Si coexists with Fe to produce an Al—Fe—Si intermetallic compound, and the dispersion of the compound refines the recrystallized structure, and these compounds serve as starting points for pit generation during the electrolytic treatment. Uniform formation of pits and fine distribution of pits. The preferable content of Si is in the range of 0.03 to 0.15%, and if it is less than 0.03%, the distribution of the compound becomes nonuniform, and the formation of pits during the electrolytic treatment becomes nonuniform. If it exceeds 0.15%, a coarse compound is produced, and precipitation of simple Si is likely to occur, and the uniformity of the roughened structure is lowered.

  Ti refines the ingot structure and refines the crystal grains. As a result, pit formation during the electrolytic treatment is made uniform, and streaks are prevented when processing as a printing plate is performed. The preferable content of Ti is in the range of 0.005 to 0.05%. When the content is less than 0.005%, the effect is small. When the content exceeds 0.05%, a coarse Al-Ti compound is formed. As a result, the roughened structure tends to be non-uniform. In addition, when adding B with Ti for refinement | miniaturization of an ingot structure | tissue, it is preferable to contain Ti in 0.01% or less of range.

  By concentrating Pb in the surface layer portion, the pits at the time of electrolytic treatment are refined and function to improve the uniformity of pit formation, and a desired pit pattern can be obtained. The preferable content of Pb is in the range of 2 to 30 ppm. When the content is less than 2 ppm, the effect is small, and when the content exceeds 30 ppm, the roughened structure tends to be uneven. As for the degree of concentration, it is desirable that the Pb concentration in the surface layer portion from the surface to a depth of 0.2 μm is 100 to 400 times the average Pb concentration.

  Cu is easily dissolved in aluminum and has an effect of refining pits in a content range of 0.05% or less. If the content exceeds 0.05%, the pits during the electrolytic treatment tend to be coarse and non-uniform.

  Mg forms a compound with Si and suppresses precipitation as simple Si. If the content is 0.05% or more, the pits at the time of electrolytic treatment tend to be non-uniform. A more preferable content of Mg is in the range of 0.01 to 0.03%.

  The production of an aluminum alloy plate for a lithographic printing plate according to the present invention involves ingot-making an ingot of an aluminum alloy having the above component composition by continuous casting or the like, and homogenizing the obtained ingot, followed by hot rolling, Although it is performed by hot rolling, the most characteristic point is that in the hot rolling process consisting of hot rough rolling and hot finish rolling, the rolling start temperature, the rolling end temperature, until the transition from rough rolling to finish rolling. By specifying the holding time and controlling the recrystallized grains when wound as a coil after finish rolling, a plate material of a predetermined thickness only by cold rolling without performing intermediate annealing after hot finish rolling It is in the point to.

  First, the surface of the rolled surface of the ingot of the aluminum alloy having the above composition is chamfered to remove a non-uniform structure causing streaks, and then homogenized for 1 hour or more in a temperature range of 500 to 610 ° C. Process. By this homogenization treatment, Fe and Si dissolved in supersaturation are uniformly deposited, and the etching pits formed during the electrolytic treatment become fine circles, and the printing durability is improved. When the homogenization temperature is less than 500 ° C., the precipitation of Fe and Si is not sufficient, and the pit pattern tends to be non-uniform. When the homogenization treatment is performed at a temperature exceeding 610 ° C., the amount of Fe dissolved increases, and as a result, fine precipitates that are the starting point of pit generation are reduced. If the holding time of the homogenization treatment is less than 1 hr, the precipitation of Fe and Si is insufficient and the pit pattern tends to be non-uniform.

  Hot rolling is usually performed in a hot rolling line after hot rough rolling in a rough rolling stand, and then the rolled material is transferred to a finishing rolling stand and hot finishing rolling is performed in a finishing rolling stand. In this case, the hot rough rolling starts at 430 to 500 ° C., ends at a temperature of 400 ° C. or higher, and finishes the hot rough rolling. Before moving to the finishing stand and starting hot finish rolling, the hot rough rolled material is held for 60 to 300 seconds to recrystallize the surface of the hot rough rolled material. In addition, after the hot rough rolling is completed, the Pb concentration at which the Pb concentration in the surface layer portion from the surface to the depth of 0.2 μm becomes 100 to 400 times the average Pb concentration by holding before the hot finish rolling is started. Obtainable.

  When the starting temperature of hot rough rolling is less than 430 ° C., the deformation resistance of the material is large, and the number of rolling passes is increased, thereby reducing productivity. When the temperature exceeds 500 ° C., coarse recrystallized grains are generated during rolling, and a streak-like uneven structure tends to be formed. When the end temperature of the hot rough rolling is less than 400 ° C., recrystallization due to the holding after the end of the hot rough rolling becomes insufficient, and it becomes difficult to obtain a uniform surface layer structure and it is difficult to obtain the enrichment of the Pb. Further, if the holding time after the hot rough rolling is completed and before the hot finish rolling is started is less than 60 seconds, the recrystallization is insufficient and it is difficult to obtain a uniform surface structure. Further, the difference between the Pb concentration in the surface layer portion and the average Pb concentration is small, and it becomes difficult to obtain the Pb concentration. If the time exceeding 300 seconds is maintained, recrystallized grains grow and partially coarse recrystallized grains are generated, and it is difficult to obtain fine recrystallized grains at the end of hot rolling, and the concentration of Pb is increased. It becomes difficult to obtain.

  Next, hot finish rolling is performed, and the hot finish rolling is finished at a temperature of 320 to 370 ° C. and wound as a coil. If the start temperature of hot finish rolling is less than 400 ° C., the end temperature of this hot finish rolling will be low, resulting in insufficient recrystallization and streaks. When the finish temperature of hot finish rolling is less than 320 ° C., recrystallization occurs only partially, causing streaks. When the finish temperature of hot finish rolling exceeds 370 ° C., the recrystallized grains become coarse, causing streaks.

  After performing the above hot rolling, the average recrystallized grain size in the direction orthogonal to the rolling direction of the surface layer portion of the hot finish rolled material can be reduced to 50 μm or less by winding up as a coil. After rolling, it becomes possible to make a plate material of a predetermined thickness only by cold rolling without performing intermediate annealing, and it is possible to achieve improvement in productivity and concomitant reduction in manufacturing cost, and the final after cold rolling In the rolled material, the average recrystallized grain size in the direction orthogonal to the rolling direction of the rolled material in the surface layer portion can be set to 50 μm or less to prevent unevenness in the surface quality of the printing plate.

In the present invention, it is also desirable that precipitates having a particle size of 1 to 10 μm are distributed in the matrix at 4000 to 10,000 particles / mm ² and precipitates having a particle size of more than 10 μm are distributed to 100 particles / mm ² or less. Due to the precipitate distribution, the uniform dispersibility of pits formed during the electrolytic treatment can be enhanced.

  The precipitate distribution described above is a homogenization treatment condition of 1 hour or more in the temperature range of 500 to 610 ° C, a hot rough rolling condition in which a start temperature is set to 430 to 500 ° C and an end temperature is set to 400 ° C or more. It can obtain by the combination of the holding conditions of the hot rough rolling material hold | maintained for 60 to 300 seconds after the completion of rough rolling and before the start of hot finish rolling.

  Examples of the present invention will be described below in comparison with comparative examples to demonstrate the effects of the present invention. These examples show one preferred embodiment of the present invention, and the present invention is not limited thereto.

Example 1 and Comparative Example 1
Aluminum alloy having the composition shown in Table 1 is melted and cast, and the rolled surface of the obtained ingot is chamfered by 5 mm / one side to a thickness of 500 mm, and each ingot is homogenized under the conditions shown in Table 2. Processing and hot rolling were performed, and the sheet thickness was 3 mm by hot finish rolling, and the product was wound on a coil. After the hot rolling, cold rolling was performed without performing intermediate annealing to obtain a cold rolled material having a plate thickness of 0.3 mm. In Tables 1 and 2, those outside the conditions of the present invention are underlined.

  Using the cold rolled material as a test material, the average recrystallized grain size in the direction perpendicular to the rolling direction of the surface layer portion of the rolled material was measured by the following method, and the concentration of Pb and the precipitate distribution in the surface layer portion were evaluated. . The results are shown in Table 3.

  Measurement of the average recrystallized grain size: After degreasing and cleaning the surface of the test material, mirror polishing, anodizing with Parker's solution, observing crystal grains in the polarization mode of an optical microscope, and in the direction perpendicular to the rolling direction The crystal grain size was determined by a cutting method.

Concentration of Pb in the surface layer part: Comparison between the Pb concentration in the surface layer part and the internal Pb concentration is carried out by performing depth analysis (depth profile measurement) of Pb by secondary ion mass spectrometry (SIMS), and the highest Pb concentration on the surface. It was calculated by the ratio of the number of counts and the number of counts from the inside aluminum substrate.
Precipitate distribution: A scanning electron microscope (SEM) was used to observe the reflected electron beam image on the surface of each aluminum alloy plate at a magnification of 500 times. 25 fields of view were photographed so that the area of one field of view was 0.04 mm ² , and the number of the intermetallic compounds and the particle diameter were measured by image analysis.

  Moreover, about the test material (cold rolling material), the presence or absence of a nonuniformity pattern and streak was observed by the following method, and the evaluation about generation | occurrence | production of an unetched part and the evaluation of the uniformity of an etch pit were performed. The results are shown in Table 4.

Degrease the cold rolled material (solution: 5% sodium hydroxide, temperature: 60 ° C., time: 10 seconds) -neutralization treatment (solution: 10% nitric acid, temperature: 20 ° C., time: 30 seconds) -AC electrolysis Roughening treatment (solution: 2.0% hydrochloric acid, temperature: 25 ° C., frequency: 50 Hz, current density: 60 A / dm ² , time: 20 seconds) -desmut treatment (solution: 5% sodium hydroxide, temperature: 60 (° C., time: 5 seconds) -anodic oxidation treatment (solution: 30% sulfuric acid-temperature: 20 ° C., time: 60 seconds), washed with water, dried, cut into a certain size to obtain a test piece.

About each test piece, the presence or absence of a nonuniform pattern and streak was observed. In addition, using a scanning electron microscope (SEM), the surface was observed at a magnification of 500 times, and a photograph was taken so that the area of the visual field was 0.04 mm ^2. Pit uniformity was evaluated.

Observation of presence / absence of uneven pattern: A case where the uneven pattern was visually observed on the surface of the test piece was evaluated as bad (×), and a case where the uneven pattern was not observed was evaluated as good (◯).
Observation of presence / absence of streak: Evaluation was made that a streak was visually observed on the surface of the test piece as defective (X), and a streak was not observed as good (O).
Evaluation of occurrence of unetched (unetched) part: An unetched part exceeding 20% was judged as defective (x), and a part not exceeding 20% was judged good (◯).
Evaluation of uniformity of etch pits (pits): Large pits with an equivalent circle diameter exceeding 10 μm are defective (×) when the area ratio exceeds 10% with respect to all pits, and those with 10% or less are good (◯) It was.

  As can be seen from Table 4, all of the test materials 1 to 4 according to the present invention do not cause uneven patterns and streaks, have excellent etching properties after electrolytic treatment, and have uniform etching pits formed on the entire surface. .

  On the other hand, since the test material 5 has a small amount of Pb, sufficient surface roughening cannot be obtained in the electrolytic treatment, and since the test material 6 has a large amount of Pb, the uniformity of pits in the surface roughening processing is lowered. did.

  Since the test material 7 has a long holding time from the end of hot rough rolling to the start of hot finish rolling, the recrystallized grains grow to form partially coarse recrystallized grains. Fine recrystallized grains cannot be obtained, and a predetermined Pb enrichment cannot be obtained, and the test material 8 has a short holding time after the hot rough rolling to the start of hot finish rolling. Due to insufficient crystal, a uniform recrystallized structure cannot be obtained in the surface layer portion of the plate, and a predetermined Pb concentration cannot be obtained. It was inferior.

  The test material 9 had a low finish temperature of hot finish rolling, and recrystallization was not sufficiently performed, resulting in non-recrystallized portions, resulting in uneven patterns and streaks, and poor pit uniformity during electrolytic treatment. . Since the test material 10 had a low homogenization temperature, the precipitation of Fe and Si was not sufficient, the pit pattern during the electrolytic treatment became non-uniform, and an unetched part also occurred.

Claims (5)

Si: 0.03 to 0.15% (mass%, the same applies hereinafter), Fe: 0.2 to 0.6%, Ti: 0.005 to 0.05%, Pb: 2 to 30 ppm, the balance It has a composition consisting of aluminum and inevitable impurities, the average recrystallized grain size in the direction orthogonal to the rolling direction of the surface layer part is 50 μm or less, and the Pb concentration in the surface layer part from the surface to a depth of 0.2 μm is 100 of the average Pb concentration. An aluminum alloy plate for a lithographic printing plate, characterized in that it is -400 times. 2. The aluminum alloy plate for a lithographic printing plate according to claim 1, comprising Cu: 0.05% or less. 3. The aluminum alloy plate for a lithographic printing plate according to claim 1, wherein Mg: less than 0.05% is contained. In the matrix, precipitates having a particle size (equivalent circle diameter, the same shall apply hereinafter) of 1 to 10 μm are distributed in a range of 4000 to 10000 / mm ² , and precipitates having a particle size of more than 10 μm are distributed in 100 / mm ² or less An aluminum alloy plate for a lithographic printing plate according to any one of claims 1 to 3. The ingot of the aluminum alloy according to any one of claims 1 to 3, after homogenizing for 1 hour or more in a temperature range of 500 to 610 ° C, a start temperature is set to 430 to 500 ° C, and an end temperature is set to 400 ° C or more. After the hot rough rolling is completed, the hot rough rolled material is held for 60 to 300 seconds before the hot finish rolling is started, and then the surface of the hot rough rolled material is recrystallized. A method for producing an aluminum alloy plate for a lithographic printing plate, comprising performing hot finish rolling, finishing hot finish rolling at a temperature of 330 ° C. or more, and performing cold rolling with a workability of 80% or more.